Water-tube boiler



July 9, 1929. p,' c s 1.720.469

' WATER TUBE BOILER Filed June 20, 1927 2 Sheeis-Sheet 1 ATTORNEY July 9, 1929. c s 1,720.469

WATER TUBE BOILER Filed June 20, 1927 2 Sheets-Sheet, 2

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IPEBGIVAL FRANCIS CRINKS, OI SIDCUP, ENGLAND, ASBIGNOB TO 'VIGIEBB BOILER COMPANY LIMITED, 01 LONDON, ENGLAND; A COMPANY 01' GREAT BRITAIN.

, WATEB TUBE BOILER.

Application filed June 2b, 1927, Serial No. 200,214, and in Great Britain July M, 1926.

This invention relates to improvements in water tube boilers and has for its ob ec t to construct an improved boiler of the threedrum type. This type of boiler usually comprises essentially a main steam and water drum, a lower drum or water drum below the main drum and connected therewith by a bank of downcomer tubes, a stabilizing drum at approximately the same level as the main drum and connected thereto by horizontal cross-connector tubes, and an inclined bank of evaporative tubes which are heated intensely by the furnace gases being interposed between the lower drum and the stabilizing drum.

An object of this invention is the provision of a lower or water drum in which the formation of zones of comparatively cool or stagnant water, particularly in contact with the shell thereof, is prevented, the drum being thereby maintained at a substantially equal temperature.

A further object is to provide a lower or water drum in which sludge and impurities contained in the water fed to the boiler may be deposited, such water then being heated in a suitable part of the boiler and circulated at increased velocity around the lower drum.

The invention also aims to provide a water tube boiler of the three drumtype of generally improved construction and steam generating performance which is extremely suitable for dealing satisfactorily with fluctuating demands thereon.

These and other objects of the invention will be apparent from the following description with reference to the accompanying drawings which show a preferred construc-' tion of boiler according to the invention.

Tn the drawings Fig. 1 is a side sectional elevation of a three-drum boiler, equipped in this example with water walls, Fig. 2 shows front elevations of the boiler, the left-hand and right-hand portions being taken substantially on lines A-B and fl D respectively of Fig. 1, and Fig. 3 represents a sectional plan of the main steam and water drum, part being broken away.

In the boiler shown a feed water deaer-ating trough 1 is provided in the main steam andwater drum 2 spaced from the shell thereof, quill pipes 3 serving to conduct water from the feed water compartment or trough 1 into certain of the downcomer tubes 4 which pass through the shell 5 of the lower drum and terminate within the cylindrical settling chamber 6 which is defined by an inner shell or bafile 6 of substantially cylindrical form. Other tubes 4 which serve as risers also communicate with the settlin chamber 6 and with the main drum 2, while further sets of downcomers h, 9 afford communication between the main drum n and the annular chamber 7 surrounding the settling chamber 6. Two sets of evaporative tubes l0, ll. connect the annular chamber 2 and the stabilising drum l2, a longitudinal. fin or partition l3 bemg disposed radially within said annular chamber between the sets of tubes l0, ll. Horizontal cross-connector tubes l l connect the stabilizing drum 1% and the main drum Q, a splash plate 15 being provided in the lat ter as is usual opposite the open ends of the tubes 14.

A division plate or babe 16 extends longitudinally through the main steam drum, as may bereadily seen in Fig. 3, separating the open ends of tubes 4, d, from the remainder of the tubes entering the drum 2 the ends of said plate terminating short of the ends of the drum and being formed substantially E-shaped so as to embrace a few tubes of the outer row of tubes 9. The steam generated is drawn off from the main drum y a steam pipe l7 furnished in the usual manner with a superheater l8.

The path of the furnace gases is indicated by arrows at in Fig. T, from which it is seen that the gases first pass up between eraporative tubes 11, it) around a hams 19 which extends from the lower drum between the sets of tubes ll, lb and terminates vertically about the middle of the boiler. The gases thereafter pass around tubes ll, superheater tlll llli

18, evaporative tubes lll, vertical tubes h, 8,

illi

mainder of the tubes. All the water tubes are straight, except at the ends, where they curve gently so as to enter the respective drums radially.

The system of circulation com rises three sta es which may be traced as fol ows irst a low velocity circuit of water from the side of the drum 2 remote from tubes 14, together with feed water entrained through quill pipes 3 from the feed deaerating trough 1, asses into heated downcomers 4 to the sett ing chamber 6, and after circulatin' therein passes back to the main drum 2 t rough the tubes 4'. The second or intermediate velocity circuit water is drawn from the water, in drum 2, which is adjacent to tubes 14. together with water entrained from the first velocity circuit in the main drum as hereinafter described, passes through downcomers 9 into annular chamber 7 of the water drum, around the u per portion of which it circulates as in icated by arrows b to the upper series of evaporative tubes 10 and is intensely heated as it passes to the stabilizing drum and through cross-connector tubes 14 back to the main drum 2. The third circuit consists of water flowing at high velocity from the main drum 2 into downcomers 8 to the annular chamber 7 around the lower part of which M it passes as indicated by arrows c, enters the lower series of evaporative. tubes 11' to the stabilizing drum 12, and finally passes through cross-connector tubes 14 to the main drum 2. The flow of water and steam is in-v dicated generally in the drawing by appropriate arrows.

It will be understood that in normal operation the water may circulate several times through each stage before passing to the subsequent stage. For instance, the water in the low velocity circuit may circulate reeatedly around tubes 4 and 4, so that any oreign matter that it contains is deposited in the settling chamber 6. As demands for steam are made upon the boiler however, the

water is drawn away around the end of the division plate 16 into the end tubes of downcomers 9 which are embraced by said plate (see Fig. 3). Some of the water issuing from the cross-connectors 14 will also pass into said end tubes of downcomers 9 and mixing with the water coming from the low velocity stage, will immediately raise its temperature substantially to that of the intermediate velocity stage. The water entering drum 2 from tubes 14 will pass below splash plate 15, that having the greatest velocity will enter downcomers 8, whilst the remainder enters downcomers 9.

The provision of a single longitudinal partition or fin 13 within the annular chamber 7 is generally suflicient to ensure that water enterin said chamber from the downcomers 9 will ow-in the direction indicated by arrows 6 into the tubes 10 while that from downcomers 8 flows in the opposite direction to tubes 11, but ifdesired a further longitudinal fin 21 may be provided in the annular chamber between the ends of tubes 8 and 9. so that the division of the intermediate and low velocity circuits within the annular chamber is lpositively effected, although this division wi 1 take place quite satisfactorily Without such fin 21. Alternatively the bafile or fin 13 may be disposed between the ends of tubes 9 and 10, so that the water from downcomers 8 and 9 flows in a combined stream around the lower part of the annular chamber to the evaporative tubes 11, 10.

With the boiler above described it is evident that the comparative cool water fed into the boiler does not come into contact with the shell of the main drum or with the shell of the lower drum before it is heated very considerably and has been thoroughly deaerated and caused to deposit its impurities into a separate chamber from which they can be readily removed in the usual manner by blowing down. The shells of drums 2 and 5, being thus maintained at a substantially uniform temperature, are not subject to distortion and stress due to unequal expansion which has usually been the case with this type of boiler. oreover, since the water only comes into contact with the outer shell of drum 5 after passing through a bank of heated tubes 4-, then through the settling chamber, then throu h a second bank of heated tubes 4' and then t rough a third bank of heated tubes 8, it is in a considerably heated and purified condition before it enters the annular chamber 7 round which it flows at a relatively high velocity to the evaporating tubes 10 and 11.

p The circuits can obviously be somewhat modified and substantialimprovement still be obtained over existing boilers, for example, the tubes 4' may be disposed parallel to the tubes 10, 11 and be connected between thc set tling chamber 6 and the stabilizing drum 12, but it is not preferable to use such an arrangement where the feed water contains any substantial amount of impurities.

The construction of the lower drum with its settling chamber may be carried out in various forms, for example, the settling chamber may comprise an open-ended cylindrical shell extending approximately to the ends of the shell 5 where it is supported upon angle pieces 22 as indicated in Fig. 2, or said inner shell may terminate before reaching the ends of shell 5 and may be provided with sill plates to retain the sludge therein.

The tubes 4, 4' which pass through the shell 5 into the chamber 6 may be mounted in any convenient manner, for example, they may be expanded in said shell in the usual manner and their ends extended to project through the walls of the settling chamber 6, or additional short tubes may extend between said ends and the settling chamber. Obviously it ill) ill

is not necessary that the joints of the chamber 6 should be water or steam tight and said chamber ma be constructed sothat it can readily be ta (en to pieces when desired. One or more sludge valves 23 opening from the chamber 6 and blow-off valves 24 mounted upon the shell'5 may be rovided as will be t conduct water at high temperature and velocity and therefore already puried, to lower headers 26 extending around the sides of the combustion chamber and connected b banks of vertical tubes 27 with upper hea ers Q8 connected to the stabilizing drum 12. The rear bank of tubes preferably communicates directly with the drum l2, while the trout banlrmay advantageously be arranged to re-enter the annular chamber 7 of the lower drum as is clearly shown in Fig. 1, boiler drain cochs Q9 being also provided at the foot of downcomers Q5. The water walls thus constitute a branch circuit between the annular chamber and the stabilizing drum so that the water passing therethrough has already been heated to a relatively high temperature and thereby purified.

The invention is not to be confused with arrangements in which a water tube of normal size passes through the lower drum of a boiler.

T he inner shell 6 employed according to this invention is of a much greater diameter than the water tubes; it is preferably of the order oil one-half the diameter of the drum 5 or more, so that the annular chamber 7 is of relatively restricted width and a brisk and uniform circulation around the drum 5 is as sured. ln the example illustrated, the respective diameters of the shell 6' and drum 5 are so chosen that the volumes of the chambers '6 and 7 are approximately equal.

By the means above described it is evident that a continuous circulation is maintained within the boiler, and particularly within those portions of the lower drum which are connected to the evaporating tubes 10, ll and as a direct resultot this priming or surging in the boiler when increased demands for steam are made, is obviated,'there being no zones of comparatively stagnant or cool water which are suddenly set in motion and drawn into the evaporating tubes. Further, the walls of the drum 5 are maintained at a uniform high temperature, and the provision of a separate sludge compartmentcommunieating with only a few tubes causes the uselul life of the tubes as a whole to be prolonged, the corrosive action being practically confined to these few tubes, and the sludge compartment which can readily be renewed when necessary. Incidentally as'the sludge is retained in the drum compartment intended for its rece tion, there is no danger of its fouling the tu s and it can readily be dischar ed when desired.

I c aim as my invention 2- 1. In a water tube boiler, a main steam and water drum, a water drum comprising an outer shell and an inner shell secured within and spaced from the outer shell to define an annular water circulating chamber, said inner shell constituting a settllng chamber, a stabilizing drum, tubes connecting said settling chamber with the main drum, tubes connecting said main drum with said annular chamber, a longitudinal bathe in said main drum disposed between the ends of the tubes connecting said main drum with the settling chamber and annular chamber respectively, said bafile' terminating short of the ends of the main drum and having shaped ends disposed between the ends of said main drum and certain of the tubes connecting said drum to the annular chamber, tubes connecting the stabilizing drum with the main drum, tubes connecting the stabilizing drum with the annular chamber, and a longitudinal bade in said annular chamber disposed between the ends of certain of the last mentioned tubes.

2. In a water tube boiler, an upper drum; a lower drum comprisin an outer shell and an inner shell secured wit in and spaced from the outer shell to define an inner settling chamber and an annular water circulating chamber therearound; means for supplying water to said settling chamber; water tubes connecting said settlingchamber and upper drum; downcomer tubes connecting said up per drum and annular chamber; a tubular steam enerating system connecting said annular c amber and upper drum; and means for directing the circulation of water from said downcomers to said generating system around the lower part of said annular chamber.

3. In a water tube boiler, an upper drum; a lower drum comprising an outer shell and an inner shell secured within and spaced from the outer shell to define an inner settling chamber and an annular water circulating chamber therearound; downcomers connecting said drum and annular chamber; a steam generating system connecting said an nular chamber and upper drum and compris ing evaporating tubes connected to said annular chamber; longitudinal badle means in the upper region of said annular chamber between certain o'l said downcomers and evaporating tubes; means for supplying water to the settling chamber; and risers con necting said settling chamber and upper drum.

4. In a water tube boiler, an upper drum: a lower drum comprising an outer shell and an inner shell secured within and spaced from llil llli

the outer shell to define an inner settling chamber and an annular water circulating chamber therearound; downcomers connecting said upper drum and annular chamber; a steam generating system connecting said annular chamber and upper drum and comprising evaporating tubes connected to said annular chamber; longitudinal baflie means disposed in said annular chamber intermediate the ends of certain of said evaporating tubes; means for supplying water to the settling chamber; and risers connecting said settling chamber and upper drum.

5. In a water tube boiler, an upper drum; a lower drum comprising an outer shell and an inner shell secured within and spaced from the outer shell to define an inner settling chamber and an annular water circulating chamber therearound; downcomers connecting said upper drum and annular chamber: a steam generating system connecting said annular chamber and upper drum and comprising evaporating tubes connected to said annular chamber; a longitudinal baflle extending across said annular chamber intermediate the ends of certain of said downcomers; a second longitudinal baliie extending across said annular chamber intermediate the ends of certain of said evaporating tubes: means for supplying water to said settling chamber; and risers connecting said settling chamber and upper drum.

6. In a water tube boiler, an upper drum; a lower drum comprising an outer shell and an inner shell having a diameter not less than half that of the outer shell secured Within and spaced from said outer shell to define an inner settling chamber'and an annular water circulating chamber therearound; a tubular circuit including said upper drum and inner settling chamber; a second tubular circuit including'said upper drum and annular chamber; and means for directing the circulation of water in said second tubular circuit around the lower portion of said annular chamber.

7. In a Water tube boiler. an upper drum; a lower drum comprising an outer shell and an inner shell secured within and spaced from said outer shell to define an inner settling chamber and an annular Water circulating chamber therearound; a. tubular circuit including said upper drum and the settling chamber; a second tubular circuit including said upper drum and annular chamber; and longitudinal baffle means disposed in the upper region of said annular chamber between the entering and leaving portions of said second tubular circuit.

8. In a water tube boiler, a main steam and water drum; a feed water compartment therein; a lower drum comprising an outer shell and an inner shell having a diameter not less than half that of the outer shell secured within and spaced from the outer shell to define an inner settling chamber and an annular water circulating chamber therearound; downcomers connecting said feed water compartment and settling chamber; a return tubular connection between said settling chamber and upper drum; downcomers connecting said main drum and annular chamber; and a return tubular connection between said annular chamber and main drum.

9. In a water tube boiler, a main steam and water drum and a feed water compartment therein; a lower drum comprising an outer shell and an inner shell secured within and spaced from the outer shell to define an inner settlin chamber and an annular water circulating c amber therearound; tubes connecting said feed water compartment and settling chamber; a return tubular connection between said settling chamber and upper drum; downcomers connecting said main drum and annular chamber and a second return tubular connection between said annular chamber and main drum; and longitudinal bafiie means in the upper region of said annular chamber between certain of said downcomers and at least a portion of said second return connection.

10. In a Water tube boiler, a main steam and water drum; a feed water trough therein; a lower drum comprising an outer shell and an inner shell secured within and spaced from said outer shell to define an inner settling chamber and an annular water circulating chamber therearound; tubes connecting said settling chamber with the main drum; quill pipes between the feed water trough and certain of said tubes; a tubular return connection between said settling chamber and main drum; downcomers connecting the main drum with the annular circulatin chamber; a second tubular return connection between said annular chamber and main drum; and longitudinal battle means in the upper region of said annular chamber between certain of said downcomers and at least a portion of said second return connection.

11. In awater tube boiler, a main steam and water drum a feed water compartment therein; a water drum comprising an outer shell and an inner shell having a diameter not less than half that of the outer shell secured within and spaced from said outer shell to define an inner settling chamber and an annular water circulating chamber therearound; tubes connecting said feed water compartment and the settling chamber; downcomersconnecting the main drum with the annular chamber; a stabilizing drum; tubes connecting said annular chamber and stabilizing drum; and tubes connecting said stabilizing drum and main drum.

12. In a water tube boiler, 21 main steam and water drum; a feed water compartment therein; a water drum comprising an outer shell and an inner shell secured within and spaced from said outer shell to define an inner settling chamber and an annular water circulating chamber therearound; tubes connecting said feed water compartment and the settling chamber; downcomers connecting the main drum with the annular chamber; a stabilizi-ng drum; tubes connecting said annular chamber and stabilizing drum; tubes connecting said stabilizing drum and main drum; and longitudinal baflle means disposed in the upper region of said annular chamber between certain of said downcomers and the tubes connecting said chamber with the stabilizin drum.

13. n a Water tube boiler, a main steam and water drum; a feed water compartment therein; a water drum comprising an outer shell and an inner shell secured within and spaced from said outer shell to define an inner settling chamber and an annular water circulating chamber therearound; tubes connecting said feed water compartment with the settling chamber; a tubular return connection between said settling chamber and main drum; downcomers connecting said main drum and annular chamber; a stabilizing drum; tubes connecting said stabilizing drum and main drum; evaporating tubes connecting said annular chamber and stabilizing drum; and a longitudinal battle disposed in said annular chamber intermediate the ends of certain of said evaporating tubes.

14. In a Water tube boiler, a main steam and water drum a feed water compartment therein; a water drum comprising an outer shell and an inner shell secured within and spaced from said outer shell to define an inner sett ling chamber and an annular water circulat- 1n chamber therearound; tubes connectlng said feed Water compartment wlth the settling chamber, a tubular return connection between said settling chamber and main drum; downcomers connecting said main drum and annular chamber; a stabilizing drum; tubes connectingsaid stabilizing drum and main drum; evaporating tubes connecting said annular chamber and stabilizing drum; a longitudinal baffle disposed in said annular chamber intermediate the ends of certain of said evaporating tubes; and a longitudinal baflie disposed in said annular chamber intermediate the ends of certain of said downcomers.

15. In a water tube boiler, a main steam and water drum; a feed water compartment therein; a water drum comprising an outer shell and an inner shell secured within and spaced from said outer shell to define an inner settling chamber and an annular water circulating chamber therearound; tubes connecting said feed water compartment and the settling chamber downcomers connecting the main drum with the annular chamber; a stabilizing drum; tubes connecting said stabilizing drum and main drum; and tubes connecting said annular chamber and stabilizing drum and including a water tube furnace Wall system connected between the lower region of the annular chamber and the stabilizing drum.

In testimony whereof I have hereunto subscribed my name this tenth day of June, 1927.

PERCIVAL FRANCIS ORINKS. 

